Fix our default fastbuild Bazel config
#4363
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Causes the default development (`fastbuild`) Bazel build and test to both use ASan, minimal optimizations, and produce good backtraces with source locations. This also fixes all of the non-host configs that were deeply broken for the latest releases of Bazel going back quite some time. The intent of our our Bazel toolchain config was for a minimally optimized, minimal debug info, and ASan + UBSan configuration to be the `fastbuild`, or the default development build of the project. This matches its inclusion of asserts, etc. At some point quite some time ago, all of this stopped working. Bazel no longer has a `nonhost` feature. This was disabled a long time ago, briefly argued to be re-enabled, but has persistently been removed. However, since then the host and non-host features have been separated including the compilation mode, and so none of that is needed now. Instead, we can use a much simpler and more principled approach to all of the feature configuration now which this PR implements. However, we added TCMalloc _after_ all of the ASan stuff became broken, and so we never saw that it is fundamentally incompatible with ASan. So this PR also reworks how TCMalloc is used to only apply to `-c opt` builds on Linux, and it also explicitly disables it when using `--config=asan`. I've not found a convenient way to tie the malloc library choice to a toolchain feature in Bazel, so this relies on the config being used rather than the feature in isolation. Last but not least, with this change `fastbuild` creates substantially larger output and so this change also passes several new flags to reduce the size costs. One is a general improvement from outlining ASan instrumentation. The others are in a special feature as they reduce the error message quality for two of the more expensive UBSan checks in favor of small generated code size. Keeping these last two separate allows disabling this locally if needed to debug a failure.
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FYI, this should be ready to go! =] |
josh11b
approved these changes
Oct 7, 2024
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Oct 25, 2024
AFAICT #4363 made builds of extract.cpp go from ~15s to ~35s. I'm not sure how to really improve on this, short of adding boilerplate to the types in order to reduce template use (e.g., instead of using struct reflection to return fields, we could have something that directly returns fields). But, this switch to `MaybeTrace` seems to be about a 20% build time improvement (down to ~30s), with `noinline` accounting for a part of that.
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https://bazel.build/rules/lib/core/dict#update indicates it returns `None`. Maybe this hasn't worked for a long time, and was missed due to the issue fixed by #4363
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Causes the default development (
fastbuild) Bazel build and test to both use ASan, minimal optimizations, and produce good backtraces with source locations.This also fixes all of the non-host configs that were deeply broken for the latest releases of Bazel going back quite some time.
The intent of our our Bazel toolchain config was for a minimally optimized, minimal debug info, and ASan + UBSan configuration to be the
fastbuild, or the default development build of the project. This matches its inclusion of asserts, etc.At some point quite some time ago, all of this stopped working. Bazel no longer has a
nonhostfeature. This was disabled a long time ago, briefly argued to be re-enabled, but has persistently been removed. However, since then the host and non-host features have been separated including the compilation mode, and so none of that is needed now. Instead, we can use a much simpler and more principled approach to all of the feature configuration now which this PR implements.However, we added TCMalloc after all of the ASan stuff became broken, and so we never saw that it is fundamentally incompatible with ASan. So this PR also reworks how TCMalloc is used to only apply to
-c optbuilds on Linux, and it also explicitly disables it when using--config=asan. I've not found a convenient way to tie the malloc library choice to a toolchain feature in Bazel, so this relies on the config being used rather than the feature in isolation.Last but not least, with this change
fastbuildcreates substantially larger output and so this change also passes several new flags to reduce the size costs. One is a general improvement from outlining ASan instrumentation. The others are in a special feature as they reduce the error message quality for two of the more expensive UBSan checks in favor of small generated code size. Keeping these last two separate allows disabling this locally if needed to debug a failure.